Emídio Vasconcelos Leitão da Cunha

Natural products inhibitors of the enzyme acetylcholinesterase

Alzheimers disease (AD) is a progressive, neurodegenerative pathology that primarily affects the elderly population, and is estimated to account for 50-60% of dementia cases in persons over 65 years of age. The main symptoms associated with AD involve cognitive dysfunction, primarily memory loss. Other features associated with the later stages of AD include language deficits, depression, behavioural problems including agitation, mood disturbances and psychosis. One of the most promising approaches for treating this disease is to enhance the acetylcholine level in the brain using acetylcholinesterase (AChE) inhibitors. The present work reviews the literature on plants and plant-derived compounds inhibitors of enzyme acetylcholinesterase. The review refers to 309 plant extracts and 260 compounds isolated from plants, which are classified in appropriate chemical groups and model tested, and cites their activity. For this purpose 175 references were consulted.

Natural products inhibitors of the angiotensin converting enzyme (ACE): a review between 1980 - 2000

Inhibition of Angiotensin Converting Enzyme (ACE) is a modern therapeutic target in the treatment of hypertension. Within the enzyme cascade of the renin-angiotensin system, ACE removes histidyl-leucine from angiotensin I to form the physiologically active octapeptide angiotensin II, one of the most potent known vasoconstrictors. Therefore, a rationale for treating hypertension would be to administer drugs or natural compounds which selectively inhibit ACE. The present work constitutes a review of the literature of plants and chemically defined molecules from natural sources with in vitro anti-hypertensive potential based on the inhibition of ACE. The review refers to 321 plants, the parts utilized, type of extract and whether they are active or not. It includes also the names of 158 compounds isolated from higher plants, marine sponges and algae, fungi and snake venom. Some aspects of recent research with natural products directed to produce anti-hypertensive drugs are discussed. In this review, 148 references were cited.

Natural products with antileprotic activity

Leprosy is a chronic infectious disease caused by Mycobacterium leprae bacillus. It was considered to be an incurable disease for ages. Nowadays leprosy is a vanishing disease although we can meet it principally in the tropical zone countries. Brazil has the second greatest number of leprosy cases around the world with almost 30,000 new cases diagnosed in 2005. The present work constitutes a literature review on plant extracts and chemically defined molecules of natural origin showing antileprotic activity. The review refers to 11 plants, their families, and geographical distribution, the utilized parts, the type of extract and the tested organism. It also includes 17 compounds isolated from higher plants and microorganisms, classified into appropriate chemical groups. Some aspects of recent antileprotic-activity-directed research on natural products are discussed. For this purpose 63 references were consulted.

Essential Oil of Mentha x villosa Huds. from Northeastern Brazil

Abstract An oil produced from Mentha x villosa Huds. by steam distillation of plant material collected in Fortaleza was analyzed by GC/MS and retention indices. The oil was found to be rich in piperitenone oxide (55.4%) and γ-muurolene (13.1%).

Brominated Compounds from Marine Sponges of the Genus Aplysina and a Compilation of Their 13C NMR Spectral Data

Aplysina is the best representative genus of the family Aplysinidae. Halogenated substances are its main class of metabolites. These substances contribute greatly to the chemotaxonomy and characterization of the sponges belonging to this genus. Due to their pharmacological activities, these alkaloids are of special interest. The chemistry of halogenated substances and of the alkaloids has long been extensively studied in terrestrial organisms, while the number of marine organisms studied has just started to increase in the last decades. This review describes 101 halogenated substances from 14 species of Aplysina from different parts of the world. These substances can be divided into the following classes: bromotyramines (A), cavernicolins (B), hydroverongiaquinols (C), bromotyrosineketals (D), bromotyrosine lactone derivatives (E), oxazolidones (F), spiroisoxazolines (G), verongiabenzenoids (H), verongiaquinols (I), and dibromocyclohexadienes (J). A compilation of their 13C NMR data is also part of the review. For this purpose 138 references were consulted.

Isoflavone formononetin from red propolis acts as a fungicide against Candida sp.

A bioassay-guided fractionation of two samples of Brazilian red propolis (from Igarassu, PE, Brazil, hereinafter propolis 1 and 2) was conducted in order to determine the components responsible for its antimicrobial activity, especially against Candida spp. Samples of both the crude powdered resin and the crude ethanolic extract of propolis from both locations inhibited the growth of all 12 tested Candida strains, with a minimum inhibitory concentration of 256 μg/mL. The hexane, acetate and methanol fractions of propolis 1 also inhibited all strains with minimum inhibitory concentration values ranging from 128 to 512 μg/mL for the six bacteria tested and from 32 to 1024 μg/mL for the yeasts. Similarly, hexane and acetate fractions of propolis sample 2 inhibited all microorganisms tested, with minimum inhibitory concentration values of 512 μg/mL for bacteria and 32 μg/mL for yeasts. The extracts were analyzed by HPLC and their phenolic profile allowed us to identify and quantitate one phenolic acid and seven flavonoids in the crude ethanolic extract. Formononetin and pinocembrin were the major constituents amongst the identified compounds. Formononetin was detected in all extracts and fractions tested, except for the methanolic fraction of sample 2. The isolated isoflavone formononetin inhibited the growth of all the microorganisms tested, with a minimum inhibitory concentration of 200 μg/mL for the six bacteria strains tested and 25 μg/mL for the six yeasts. Formononetin also exhibited fungicidal activity against five of the six yeasts tested. Taken together our results demonstrate that the isoflavone formononetin is implicated in the reported antimicrobial activity of red propolis.

A triterpenoid from the root-bark of Chiococca alba

Abstract A new triterpenoid with an oleanolic acid skeleton was isolated from the root-bark of Chiococca alba and identified as 3β-hydroxyolean-12,15-dien-28-oic acid.

Chemical and pharmacological investigation of Solanum species of Brazil: a search for solasodine and other potentially useful therapeutic agents

A systematic search for solasodine, an important starting material for the partial synthesis of steroidal hormones as well as other potentially bioactive constituents of various Solanum species of Brazil has been undertaken. Thus, the fruits of S. paludosum, S. asperum, S. sessiliflorum and Solanum sp. were found to contain significant amounts of solasodine. The root bark of S. paludosum which showed curare like activity yielded tomatidenol and another yet unidentified alkaloid responsible for the biological activity. The fruits of S. asperum yielded a new spirosolane alkaloid, solaparnaine. The stem bark of S. pseudo-quina showed convulsive and excitatory activity from which (25S)-isosolafloridine was identified as the active principle. In addition, the latter alkaloid was also found to show antimicrobial activity.

ESSENTIAL OIL OF Protium unifoliolatum (BURSERACEAE)

The major constituents of the leaf essential oil of P. unifoliolatumare trans-caryophyllene (37.45%), limonene (24.23%) and α-humulene (9.94%).

Isolamento e identificação de novos alcalóides de Ocotea duckei Vattimo (Lauraceae)

Three benzylisoquinoline alkaloids, reticuline, coclaurine, and N-acetyl norjuziphine, where isolated from the stem bark of Ocotea duckei, the calix yielded laurelliptine, an aporphine alkaloid. These substances were isolated by chromatographic methods and identified by 1H and 13C NMR spectroscopy with the aid of 2-D techniques such as COSY, NOESY, HMQC and HMBC. Comparison with literature data was also helpful.